Radiator core construction



Dec. 6, 1938. 1 v N. KEARNEY 2,139,367

RADIATOR CORE CONSTRUCTION Filed Nov. 20,1935

RELATIVE ,AIRFLOWI 9 5 INVENTOR. v NORMAN L. KEARNEY; BY Y Patented Dec. 6, 1938 UNITED STATES PATENT OFFICE I 2,139,367 RADIATOR 001m CONSTRUCTION Norman L. Kearney, Buffalo, N. Y., assignor, by

mesne assignments, to Curtiss-Wright Corporation, -a corporation of New York Application November 20, 1935, Serial No. 50,647 2 Claims. (01. 257-128) This invention relates to heat exchange devices a spacer which is readily positioned for assembly and more particularly to the support of tubular regardless of any axial rotation necessary to elements used therein. It is especially adapted properly position the ends of the tubes for their to the intermediate support of relatively thinassembly.

5 walled tubes used in long core radiator construc- These and other desirable objectsand advan- 5 tion as utilized in aircraft. tages of the present invention will be illustrated It has frequently been found advantageous in in the c omp y drawing and described in the design of radiators, oil coolers or other heat the specification, a Preferred embodimentbeing 1 exchange devices in aircraft, to provide cores sclosed by Way of ustr only, Since formed of relatively long tubes horizontally e u de ying princip ay be incorporated in 10 alined with the airstream, but the methods hereother specific devices, it is not intended to be tofore used in such constructions to prevent conlimited to the one here shown except as such tact due to sagging of the thin-walled tubes have limitations are clearly imposed by the pp not proven satisfactory. These prior methods c msinvariably resulted either in aspliced joint of In the accompanying drawing in which like 15 appreciable weight due to telescoping of the tube characters of reference indicate corresponding Walls and the addition of solder material, or in p ts in all t e v ews:-

the decrease in efficiency due to the disturbance Fig. 1 is a broken view of a radiator to which to both fluid and heat flow caused by the relamy invention is shown to be adapted;

tively large metallic contact area between the Fig, 2 is an enlarged elevation of a portion of 20 tubes. This also had the undesired effect of the core of the radiator; forming a balile or separator and thereby creat- Fig. 3 is an end elevation of the core portion ing' the equivalent of a two-pass radiator core. shown in Fig. 2; Other prior methods have invariably proven to Fig. 4 is a cross-sectional view as seen along be inherently weak from a structural point of the lines 44 of Fig. 2; 25 view, costly, and relatively difiicult to assemble. Fig. 5 is a cross-sectional view of a tube spacer The present invention covers briefly the proas viewed along the lines .5--5 of Fig. 4; and

vision of a-spacer or separator, havinga spheri- Fig. 6 is a cross-sectional view of a modification cal form, pressed or formed on the tube wall in which slightly larger spacers are provided on such that it spaces and supports the same equialternate series of tubes. 30

distantly from the adjacent tubes by tangential With particular reference to Fig. 1, the radia-' contact with these tubes or the spacers with tor 6 is shownattached to an aircraft body I which these tubes are similarly provided. which obviously may beeither a portion of the It is, accordingly, an object of this invention fuselage, wing or engine nacelle from which the to provide a simple and inexpensive means radiator may either be suspended or extended 35 whereby relatively long thin tubes may be mainlaterally. The radiator 6 comprises essentially a tained at a predetermined spacing from each core portion 8 consisting of a plurality of parother intermediate their ends and by which the allel spaced tubes 9 alined with the relative airtubes tend to support each other and eliminate flow for .the passage of cooling air therethrough.

40 or minimize sagging. It is also an object to pro- The core 8 is enclosed by the header l0, prefer- 40 vide such a spacing device which is light in ably of airfoil shape in cross-section, and which weight and simple and quickly applied and asmay be of either circular or semi-circular outsembled. line as viewed in the direction of the relative It is a further object to provide a tube spacer airflow indicated by the arrow in Fig. 1. which contacts the adjacent tubes or spacers A portion of the inner wall of the header I0 45 over a minimum area and which further main; positioned against the core 8 of nested tubes 9 tains an adequate space about the tubes and is removed to provide an opening H through spacers in the plane of their points of contact, to which the liquid to be cooled in the radiator may facilitate the flow of the liquid therethrough. It pass either to or from the core section 8 to the is also an object of this invention to provide such header It. It will be readily understood that the 50 a spacer which will not becoine displaced by ordinecessary piping and connections from the radianary usage and which does not require soldering tor core 8 and the header III, while not shown in or other attachment to the adjacent tubes or the drawing, will be provided in a manner well spacers. known to those acquainted with the art, in order It is a further object to provide a tube with i to complete the cooling or other system of which 55 the radiator 6 forms a part and to which this invention is particularly adapted.

As shown in Fig. 2, the core 8 of the radiator 6 comprises relatively long tubes 9, preferably of seamless copper or similar heat transmitting material, and of comparatively light gauge to conserve weight. Each tube 9 has formed at its ends hexagonal portions i2 which serve to properly space the tubes from each other, and on the outer surfaces of which, they are soldered together to form a relatively rigid end section adapted to establish the arrangement and spacing of the tubes, and to present a large frontal area for the inflow of cooling air. It will be readily understood that the air in flowing thru the interior of the tubes 9 amorbs heat from the relatively warmer water, or other liquid, in contact with the exterior of the tubes, thereby effecting the desired cooling of the liquid.

Due to the length of the tubes 9, and notwithstanding the fact that they are made as thin and light as practicable, the weight of each tube causes an appreciable deflection or sagging which is aggravated by the excessive vibration often found in aircraft structures, and unless spaced or supported intermediate their ends, this deflection results in impaired radiator efficiency and shorter service life of the tubes. These and other objections are overcome in a simple manner, and at low cost, by the use of spacers I3, which are pieces of copper or other ductile material which may be provided in strips having a segmental cross-section, one of its faces being flat and its opposite face being arcuate in outline, as may be clearly seen in the cross-section in Fig. 5. These strips are cut to the required length or approximately the circumference of a circle whose diameter is slightly less than the outside diameter of the tubes 9.

The strip is then pressed about the tube 9 at some predetermined point intermediate the tube ends where it is desired that it be supported, preferably at its mid-point in the case of a single supported tube core as shown as the drawing, or approximately at the one-third points in the case of a doubly supported radiator core. Either before or during the pressing operation, the tube 9 has its wall reduced in diameter for a distance substantially equal to the strip width as indicated at IS in Fig. 5, about which reduced portion the spacer l3 fits tightly with its ends It in closely abutting relationship. The shoulders in the tube wall-formed at the ends of the reduced portion l5 serve to prevent axial displacement of the spacer. It will also be obvious that the spacer I3 may be formed on the reduced tube portion in a manner which would permit of its rotation thereabout and which would thereby also serve the purposes of this invention.

After being formed on the tubes 9, the spacers l3 resemble balls or beads having large openings pierced or occupied by the reduced portions of the tubes 9. The only portions projecting beyond the original outer cylindrical surface of the tube is the spherical outer portion of the spacer,

which was formerly the arcuate face of the strip, the diameter of this spherical surface being substantially equal to the distance between the axes of adjoining tubes as measured laterally or equivalent to the distance across the flats of the hexagonal end portions l2 of the tubes. Therefore, when the spacers are pressed onto each tube at the same point thereon with respect to the tube ends, the tubes when brought into their nested or assembled relationship will have the flat surfaces of their hexagonal ends coinciding, and the centers and tangent, or touching points, of all the spacers lying in the same plane normal to the tube axes, which latter are then parallel to, and equidistant from each other.

This assembled relationship is readily accomplished as each spacer adopts a touching or tangential relationship with the adjacent spacer regardless of any axial rotation of the tube which may be required in order to properly position the hexagonal ends 12 for soldering or other attachment. Due to the fact that in the case of hexagona ended tubes there will be six adjacent spacers touching any given spacer in the center of a group of six, and since these six touch at tangent points only, there will be six equal clearance spaces around the surface of each spacer between the tangent points mentioned. This insures minimum restriction of liquid flow in the direction of the tube axes and from one side of a. spacer to the other. It also provides minimum contact areas between adjoining tubes, thereby preventing absorption or loss of heat from one tube to another with its resultant effect upon the efficiency of the heat exchange device.

Radiator cores which are provided with spacers as outlined in this invention are not so likely to sag or deflect under their own weight since the entire core has been found to be reinforced by the presence of the spacers notwithstanding that they are not attached but merely touch each other. It has also been found that the slight additional weight due to the spacers has no appreciable effect upon this deflection or sagging. In cases where the tubes are extremely long, such spacers have been found to minimize the extent of the sagging and to maintain the proper parallel relationship of the tubes thereby preventing chafing or rupture of the tubes which has frequently occurred in long core radiators constructed prior to this invention, due to vibration and to the inherent quality of some tubes sagging to a greater extent than others.

This invention is not limited to air-cooled radiators but is equally well adapted to use in oil coolers, condensers, water recovery apparatus for aircraft, and in fact in any tubular heat exchange device where the length of the tubes or other conditions are suchthat the tubes are required to be supported between their ends. The spacers obviously may be oi. aluminum or other suitable material, can be welded or brazed to the tube wall where it is desired not to deform the latter, and its cross section in the plane of the tube axis can be elliptical or other suitable shape so long as its cross section in the plane of its contact points remains circular and concentric with the tube axis.

In a modification of this invention as shown in Fig. 6, further savings in cost can be accomplished by providing slightly larger spacers l3a on alternate tubes 9, in which case the spacer rests against the exterior surfaces of the adjoining tubes.

It is to be understood that the drawing and the above description are for purposes of illustration only and various changes, and modifications which may occur to one skilled in the art areto be considered within the scope and spirit of this invention.

I claim as my invention:

1. In radiator construction, a plurality of parallel fluid conveying tubes having their ends attached such that a predetermined arrangement and spacing of the said tubes is obtained as considered from within the plane normal to the axes of the said tubes, the said tubes having depressed portions intermediate their ends, spacers engagine the said depressed portions, each of the said spacers being bent and pressed from a strip of material of segmental cross section about the said depressed portion of each tube such that anal movement thereon is prevented, the said srs after bending and pressing.' adopting a iorm havine round outer surfaces, such that the said ar raneement and spacing of the w are m is tained by tangential contact of the outer suriacw oi the said spacers.

said spacing means comprising a concentrically is disposed ring adapted to tangentially contact like means on adjacent equidistantly spaced tubes in the transverse plane of its greatest diameter, the said means reducing gradually in diameter as measured outwardly from the said transverse'it plane of contact and greatest diameter. 

